1. Field of the Invention
This invention relates to a membrane for membrane switches as well as to the elements thereof, in other words to a membrane that can touch switching contacts in such a way that when the latter are depressed, an electrical contact is made. Herein the switching contacts can be provided at the membrane itself as well as underneath it in the form of a pressure contact switch.
More especially a membrane is concerned which can be used in control panels with push-button operation, in which the construction of the membrane can be either single or multiple. In the latter case the membranes of the various switches form one continuous profiled layer.
Obviously, the invention also relates to any membrane-operated switches wherein a membrane according to the present invention is used.
2. Related Art
Such membrane switches are well-known and are characterized by the membrane which at its edges is rigidly fixed and can be depressed in its centre so as to realize an electrical contact. In general they offer the advantage of being simple and light-weight. The simplicity is based on the fact that no mechanical screw connections and/or clamp connections are required for securing the various parts with respect to one another, as such membrane switch mostly consists of parts glued together. Such a construction wherein the various parts are glued together also offers the advantage of being perfectly waterproof. This is especially advantageous upon using control panels in humid operation circumstances.
However, all the known types have the disadvantage that the membrane starts to tear after some time, whereby on the one hand the proper functioning of the membrane switch is prejudiced, and on the other hand it may not be waterproof any longer, which may be hazardous for the operator.
Tearing of the known membranes is mainly the result of their shape, their fixation and of the possibility of actuating them off their centre.